Method for operating iot in cellular system and system therefor

ABSTRACT

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate beyond a 4G communication system such as LTE. The present disclosure provides a method for supporting a device performing narrow band Internet of things (IoT) communication by a base station in a cellular system, the method comprising the operations of: transmitting a synchronization sequence for synchronization between the base station and the device performing the narrow IoT communication; transmitting system information including a two-bit mode indication field which indicates an operation mode for performing the narrow IoT communication, the operation corresponding to one of a plurality of operation modes; and transmitting a control channel and a data channel on the basis of parameters for the narrow band IoT communication, the parameter being included in the system information, wherein the operation modes include at least one of a standalone mode, a guard-band mode, an in-band mode in which the cellular system and the narrow band IoT communication use a common cell ID, or an in-band mode in which the cellular system and the narrow band IoT communication use different cell IDs.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a U.S. National Stage application under 35 U.S.C. §371 of an International Application No. PCT/KR2016/008060, which wasfiled on Jul. 22, 2016, and claims a priority to U.S. Provisional PatentApplication No. 62/195,571, which was filed on Jul. 22, 2015, U.S.Provisional Patent Application No. 62/232,840, which was filed on Sep.25, 2015, U.S. Provisional Patent Application No. 62/251,378, which wasfiled on Nov. 5, 2015, U.S. Provisional Patent Application No.62/291,246, which was filed on Feb. 4, 2016, and U.S. Provisional PatentApplication No. 62/307,818, which was filed on Mar. 14, 2016, thecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an operation technique for Internet ofthings (IoT) communication in a cellular system, and more particularly,to a technique of indicating an IoT operation mode.

BACKGROUND ART

To satisfy the growing demands for wireless data traffic sincecommercialization of a 4th generation (4G) communication system, effortshave been made to develop an improved 5^(th) generation (5G) or pre-5Gcommunication system. That is why the 5G or pre-5G communication systemis called a beyond 4G network communication system or a post long termevolution (post LTE) system.

To achieve high data rates, deployment of the 5G communication system ina millimeter wave (mmWave) band (for example, 60 GHz) is underconsideration. In order to mitigate propagation path loss and increase apropagation distance in the mmWave band, beamforming, massive multipleinput multiple output (massive MIMO), full dimensional MIMO (FD-MIMO),array antenna, analog beamforming, and large-scale antenna technologyhave been discussed for the 5G communication system.

Further, to improve a system network, techniques such as evolved smallcell, advanced small cell, cloud radio access network (cloud RAN),ultra-dense network, device-to-device (D2D) communication, wirelessbackhaul, moving network, cooperative communication, coordinatedmulti-point (CoMP), and interference cancellation have been developedfor the 5G communication system.

Besides, advanced coding modulation (ACM) techniques such as hybrid FSKand QAM modulation (FQAM) and sliding window superposition coding(SWSC), and advanced access techniques such as filter bank multi carrier(FBMC) and non-orthogonal multiple access (NOMA), and sparse codemultiple access (SCMA) have been developed for the 5G communicationsystem.

One significant feature of a cellular Internet of things (CIoT) networkis that the CIoT network requires enhanced coverage to enable machinetype communication (MTC). For example, one typical scenario of a CIoTservice is to provide water metering or gas metering over a cellularnetwork.

Most MTC/CIoT systems target at low-end applications which may beappropriately managed by global system for mobile communication(GSM)/general packet radio service (GPRS) due to excellent coverage andlow device cost of the GSM/GPRS. However, as more and more CIoT deviceshave been deployed in a real environment, the dependency on a GSM/GPRSnetwork has been increasing. Further, some CIoT system targets at astandalone deployment scenario through re-farming of a GSM carrierhaving a band of 200 KHz.

As LTE deployment has been developed, network operators seek to reduceoverall network maintenance cost by reducing the number of radio accesstechnologies (RATs). MCT/CIoT is a market expected to be continuouslyboosted in the future. MTC/CIoT may cause cost to an operator and maynot bring a maximum profit from a frequency spectrum, because aplurality of RATs should be maintained in MTC/CIoT. Considering that thenumber of MTC/CIoT devices is highly likely to increase, total resourcesrequired for the MTC/CIoT devices to provide services will increaseaccordingly and will be allocated inefficiently. Therefore, there is aneed for a new solution for migrating MTC/CIoT devices from a GSM/GPRSnetwork to an LTE network.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

An aspect of the present disclosure is to provide a new machine typecommunication (MTC)/cellular Internet of things (CIoT) system which maybe flexibly deployed in various manners, such as standalone deployment,deployment in a guard band of a legacy cellular system (for example,long term evolution (LTE)), or deployment within a bandwidth of thelegacy cellular system.

Technical Solution

In an aspect of the present invention, a method for supporting narrowband Internet of things (IoT) communication of a device by a basestation in a cellular system includes transmitting a synchronizationsequence for synchronization between the device performing the narrowband IoT communication and the base station, transmitting systeminformation including a 2-bit mode indication field indicating anoperation mode for the narrow band IoT communication, the operation modecorresponding to one of a plurality of operations modes, andtransmitting a control channel and a data channel based on a parameterfor the narrow band IoT communication, the parameter being included inthe system information. The operation modes include a standalone mode, aguard-band mode, an in-band mode using a common cell identifier (ID) forthe cellular system and the narrow band IoT communication, and anin-band mode using different cell IDs for the cellular system and thenarrow band IoT communication.

In another aspect of the present disclosure, a method for performingnarrow band IoT communication by a device in a cellular system includesreceiving a synchronization sequence for synchronization between thedevice and a base station of the cellular system, receiving systeminformation including a 2-bit mode indication field indicating anoperation mode for the narrow band IoT communication, the operation modecorresponding to one of a plurality of operations modes, and receiving acontrol channel and a data channel based on a parameter for the narrowband IoT communication, the parameter being included in the systeminformation. The operation modes include a standalone mode, a guard-bandmode, an in-band mode using a common cell ID for the cellular system andthe narrow band IoT communication, and an in-band mode using differentcell IDs for the cellular system and the narrow band IoT communication.

In another aspect of the present disclosure, a base station forsupporting narrow band IoT communication of a device in a cellularsystem includes a controller for controlling transmission of asynchronization sequence for synchronization between the deviceperforming the narrow band IoT communication and the base station,transmission of system information including a 2-bit mode indicationfield indicating an operation mode for the narrow band IoTcommunication, the operation mode corresponding to one of a plurality ofoperations modes, and transmission of a control channel and a datachannel based on a parameter for the narrow band IoT communication, theparameter being included in the system information, and a transceiverfor transmitting the synchronization sequence, the system information,the control channel, and the data channel under the control of thecontroller. The operation modes include a standalone mode, a guard-bandmode, an in-band mode using a common cell ID for the cellular system andthe narrow band IoT communication, and an in-band mode using differentcell IDs for the cellular system and the narrow band IoT communication.

In another aspect of the present disclosure, a device for performingnarrow band IoT communication in a cellular system includes a controllerfor controlling reception of a synchronization sequence forsynchronization between the device and a base station of the cellularsystem, reception of system information including a 2-bit modeindication field indicating an operation mode for the narrow band IoTcommunication, the operation mode corresponding to one of a plurality ofoperations modes, and reception of a control channel and a data channelbased on a parameter for the narrow band IoT communication, theparameter being included in the system information, and a transceiverfor receiving the synchronization sequence, the system information, thecontrol channel, and the data channel under the control of thecontroller. The operation modes include a standalone mode, a guard-bandmode, an in-band mode using a common cell ID for the cellular system andthe narrow band IoT communication, and an in-band mode using differentcell IDs for the cellular system and the narrow band IoT communication.

Advantageous Effects

Considering that various operation modes are supported for cellularInternet of things (CIoT), the methods for indicating a mode accordingto the present disclosure enable a CIoT system to identify a CIoToperation mode as fast as possible and perform an appropriate subsequentprocess.

Resource utilization and frequency diversity may be increased byallocating a plurality of physical resource blocks (PRBs) to a narrowband-Internet of things (NB-IoT) system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary view illustrating various deployment scenarios ofa narrow band-Internet of things (NB-IoT) system;

FIG. 2 is an exemplary view illustrating a resource grid correspondingto one subframe in an NB-IoT system;

FIG. 3 is an exemplary view illustrating the structure of an L-subframein the NB-IoT system;

FIG. 4 is an exemplary view illustrating the structure of anL-superframe in the NB-IoT system;

FIG. 5 is an exemplary view illustrating the structure of a downlinktime domain in the NB-IoT system;

FIG. 6 is an exemplary view illustrating primary synchronization signal(PSS)/secondary synchronization signal (SSS) transmissions in the NB-IoTsystem;

FIG. 7 is an exemplary view illustrating PSS transmissions in the NB-IoTsystem;

FIG. 8 is an exemplary view illustrating physical broadcast channel(PBCH) transmissions in the NB-IoT system;

FIG. 9 is an exemplary view illustrating a primary synchronizationsignal (PSS)/secondary synchronization signal (SS S)/master informationblock (MIB) transmission of the NB-IoT system in the time domain, in amanner that avoids collision with a PSS/SSS/MIB transmission of a legacysystem;

FIG. 10 is an exemplary view illustrating an NB-IoT PSS/SSS/MIBtransmission in a long term evolution time division duplex (LTE TDD)system;

FIG. 11 is an exemplary view illustrating an alternative downlink framestructure in the time domain in the NB-IoT system;

FIG. 12 is an exemplary view illustrating physical resource block (PRB)access methods in an in-band mode NB-IoT system;

FIG. 13 is an exemplary view illustrating use of a plurality of PRBs inthe in-band mode NB-IoT system;

FIG. 14 is an exemplary view illustrating a PRB blind detection methodin the NB-IoT system;

FIG. 15 is an exemplary view illustrating a PRB blind detection methodin a guard-band mode NB-IoT system;

FIG. 16 is an exemplary view illustrating a time synchronization methodbased on PSS/SSS transmission in the NB-IoT system;

FIG. 17 is an exemplary view illustrating a method for distinguishingdifferent operation modes from each other in terms of the positions anddensity of PSS/SSS symbols;

FIG. 18 is an exemplary view illustrating a method for distinguishingdifferent operation modes from each other in terms of the positions anddensity of PSS/SSS subframes;

FIG. 19 is an exemplary view illustrating another method fordistinguishing different operation modes from each other in terms of thepositions and density of PSS/SSS subframes;

FIG. 20 is an exemplary view illustrating a method for explicitlyindicating an NB-IoT mode by MIB payload;

FIG. 21 is an exemplary view illustrating another method for explicitlyindicating an NB-IoT mode by MIB payload;

FIG. 22 is an exemplary detailed view illustrating MIB payload fordifferent operation modes;

FIG. 23 is a flowchart illustrating a method for identifying a mode inan NB-IoT device;

FIG. 24 is a flowchart illustrating another method for identifying amode in an NB-IoT device;

FIG. 25 is a flowchart illustrating another method for identifying amode in an NB-IoT device;

FIG. 26 is a flowchart illustrating another method for identifying amode in an NB-IoT device;

FIG. 27 is an exemplary view illustrating an alternative design of anNB-IoT downlink frame structure;

FIG. 28 is an exemplary view illustrating a method for supporting NB-IoTcommunication in a base station according to the present disclosure;

FIG. 29 is an exemplary view illustrating a method for conducting NB-IoTcommunication in a device according to the present disclosure;

FIG. 30 is a block diagram of a base station according to the presentdisclosure; and

FIG. 31 is a block diagram of a device according to the presentdisclosure.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present disclosure will be described below in detailwith reference to the attached drawings. A detailed description of agenerally known function or structure of the present disclosure will beavoided lest it should obscure the subject matter of the presentdisclosure. Although the terms used in the present disclosure aredefined in consideration of functions in the embodiments of the presentdisclosure, the terms may be changed according to the intention of auser or an operator, or customs. Therefore, the present disclosureshould be understood, not simply by the actual terms used but by themeanings of each term lying within.

Before a detailed description of the present disclosure, some terms usedin the present disclosure may be interpreted as, but not limited to, thefollowing meanings.

A base station is an entity communicating with a terminal, which may bereferred to as a BS, a Node B (NB), an eNode B (eNB), an access point(AP), or the like.

A device is an entity communicating with a BS, which may be referred toas a narrow band-Internet of things (NB-IoT) device, a user equipment(UE), a mobile station (MS), a mobile equipment (ME), a terminal, or thelike.

CIoT represents cellular IoT and may also be referred to as NB-IoT,NB-CIoT, or narrow band-long term evolution (NB-LTE).

While the following description will be given in the context of anNB-IoT system, by way of example, the embodiments of the presentdisclosure are not limited to the NB-IoT system. Thus, the embodimentsof the present disclosure are also applicable to a 5th generation (5G)enhanced mobile broadband (eMBB) system or a massive machine typecommunication (mMTC) system. Further, while an LIE system is taken as alegacy system, the present disclosure is also applicable to othercellular systems, not limited to the LTE system.

A. NB-IoT System Deployment Scenarios

An NB-IoT system occupies a narrow bandwidth. For example, the NB-IoTsystem may use a minimum system bandwidth of 200 kHz (or 180 kHz) forboth downlink (DL) and uplink (UL). Due to occupation of a narrowbandwidth, the NB-IoT system may be deployed standalone, in a guard bandof a legacy cellular system (for example, an LTE system), or within asystem bandwidth of the legacy cellular system.

FIG. 1 is an exemplary view illustrating various deployment scenarios ofthe NB-IoT system.

Referring to FIG. 1(a), the NB-IoT system may be deployed in astandalone mode. For example, the NB-IoT system may be deployed in thestandalone mode by re-farming a global system for mobile communication(GSM) carrier 100 having a bandwidth of 200 kHz (re-farming means re-usefor another communication service).

Referring to FIG. 1(b), the LTE system may have a guard band of 200 kHzto 2 MHz (according to its system bandwidth), and the NB-IoT system maybe deployed in a guard band region 102 of the LTE system. The operationmode of the NB-IoT system deployed in the guard band region 102 may bereferred to as a guard-band mode.

Referring to FIG. 1(c), since the bandwidth of a physical resource block(PRB) is 180 kHz in the LTE system, the NB-IoT system may be deployed inany PRB 104 within a total bandwidth. The operation mode of the NB-IoTsystem deployed in the PRB 104 within the LTE bandwidth may be referredto as an in-band mode.

Further, in order to provide a scalable (adjustable) capacity, it isalso possible to allocate a plurality of PRBs to the NB-IoT system. Thisis favorable in terms of resource utilization and frequency diversity.Frequency hopping across a plurality of PRBs may further provideinterference randomization and offer sufficiently separated PRBs and anincreased diversity gain. Particularly, an operation using a pluralityof PRBs is preferable for the in-band mode. It is because the DLtransmission power of the NB-IoT system may be shared with a legacysystem (for example, an LTE system), and resources occupied by a legacycontrol channel (for example, a physical downlink control channel(PDCCH)) or a reference signal (RS) (for example, cell-specificreference signal (CRS)) will not be used by NB-IoT.

B. Time/Frequency Resource Structure of NB-IoT System

FIG. 2 is an exemplary view illustrating a resource grid correspondingto one subframe in an NB-IoT system.

An NB-IoT system supporting the in-band mode should be designed inconsideration of co-existence and compatibility with the legacy LTEsystem. To avoid negative effects on the legacy LTE system, as many LTEparameters (for example, a waveform and a subcarrier spacing) aspossible may be reused for the NB-IoT system. In FIG. 2, the resourcegrid of one PRB during one subframe in the NB-IoT system is shown, byway of example. As illustrated in FIG. 2, the resource grid of theNB-IoT system may be identical to a resource grid of the LTE system.FIG. 2(a) illustrates a resource grid in a normal cyclic prefix (CP)case, and FIG. 2(b) illustrates a resource grid in an extended CP case.

FIG. 3 is an exemplary view illustrating the structure of an L-subframein the NB-IoT system.

A more detailed time domain structure for the NB-IoT system isillustrated in FIG. 3. In the case where only one PRB is used, a longersubframe unit 300 (for example, an L-subframe including four subframes320 (4 ms)) may be defined as a minimum scheduling unit. If a shorterscheduling unit than the L-subframe 300 is required, a longer slot 310(for example, a 2-ms L-slot) may be considered.

FIG. 4 is an exemplary view illustrating the structure of anL-superframe in the NB-IoT system.

Similarly, a 40-ms L-frame 410 including 10 L-subframes 400 may bedefined. The duration of the L-frame 410 may be matched to thetransmission time interval (TTI) of a physical broadcast channel (PBCH)of the LTE system. One PBCH is transmitted repeatedly 4 times during 40ms. One L-super frame 420 may include 32 L-frames 410 and have aduration of 1280 ms.

FIG. 5 is an exemplary view illustrating the structure of a DL timedomain in the NB-IoT system.

Referring to FIG. 5, transmission channels are arranged in time divisionmultiplexing (TDM). A synchronization sequence and broadcast information(for example, system information such as a master information block(MIB)) may be transmitted together at the beginning 502 of anL-superframe 500. In general, the synchronization sequence may include aprimary synchronization sequence (PSS) and a secondary synchronizationsequence (SSS). The MIB may include a limited amount of systeminformation. The remaining system information which is not included inthe MIB may be transmitted in a system information block (SIB) 504.According to coverage requirements, the MIB frame 502 and the SIB frame504 may be transmitted repeatedly.

FIG. 6 is an exemplary view illustrating PSS/SSS transmissions in theNB-IoT system.

In the case where only one PRB is used in the NB-IoT system, a PSSand/or SSS may be repeated (transmitted) in one subframe in order toincrease the detection performance of a synchronization sequence.Similarly to the LTE system, an NB-IoT device may acquire basic systeminformation, for example, a frame timing, a CP length (normal CP orextended CP), a frequency division duplex (FDD) mode or a time divisionduplex (TDD) mode, and a cell identifier (ID), by detecting the PSS/SSS.As illustrated in FIG. 6, since a PSS 600 and an SSS 602 are positionedin different symbols of a subframe 610, a CP length and an FDD/TDD modemay be derived after successful PSS/SSS detection. FIG. 6(a) is anexemplary view illustrating a PSS/SSS transmission in the FDD mode inthe normal CP case, FIG. 6(b) is an exemplary view illustrating aPSS/SSS transmission in the FDD mode in the extended CP case, FIG. 6(c)is an exemplary view illustrating a PSS/SSS transmission in the TDD modein the normal CP case, and FIG. 6(d) is an exemplary view illustrating aPSS/SSS transmission in the TDD mode in the extended CP case.

In the NB-IoT in-band mode, it is necessary to avoid a symbol occupiedby an RS (for example, a CRS 630) and a symbol occupied by a controlchannel (for example, a PDCCH 620) for the PSS/SSS.

FIG. 7 is an exemplary view illustrating PSS transmissions in the NB-IoTsystem.

Referring to FIG. 7(a), PSS detection performance may be improved byarranging two successive symbols for a PSS transmission.

Referring to FIG. 7(b), since a PSS signal is repeated directly, an ‘A’part 702 of a PSS symbol 700 may be considered as a virtual CP of thenext PSS symbol 710. In this case, the PSS may be detected irrespectiveof a used CP length (that is, normal CP or extended CP). Further,symbol-level correction is possible. This symbol-level correction mayreduce the PSS detection complexity of a receiver.

FIG. 8 is an exemplary view illustrating PBCH transmissions in theNB-IoT system.

FIG. 8(a) illustrates resource element (RE) mapping in the in-band modein the normal CP case, FIG. 8(b) illustrates RE mapping in the in-bandmode in the extended CP case, FIG. 8(c) illustrates RE mapping in theguard-band/standalone mode in the normal CP case, and FIG. 8(d)illustrates RE mapping in the guard-band/standalone mode in the extendedCP case. System information such as a PBCH (MIB and/or SIB) and aPSS/SSS may be transmitted in the same subframe because a PSS 800 and anSSS 802 will not use all symbols in the subframe. The PSS 800 and theSSS 802 may be used for channel estimation for decoding of the PBCH.

Referring to FIGS. 8(a) and 8(b), REs (for example, 806) not occupied bythe PSS 800/SSS 802 in a subframe may be used for PBCH transmission inthe in-band mode. On the contrary, REs (for example, 804) occupied byCRSs may not be used for RE mapping for a PBCH in the in-band mode.

Referring to FIGS. 8(c) and 8(d), CRSs are not transmitted in theguard-band mode or standalone mode. Accordingly, all REs except forPSS/SSS symbols are available for a PBCH.

In the NB-IoT in-band mode, the NB-IoT system and the LTE system mayshare the power of a BS for DL transmission. Power boosting for a signalor transmission channel (for example, a PSS/SSS, an MIB, an SIB, or aPDCCH) may be considered to enhance the coverage performance of anin-band mode NB-IoT system.

FIG. 9 is an exemplary view illustrating a PSS/SSS/MIB transmission ofthe NB-IoT system in the time domain, in a manner that avoids collisionwith a PSS/SSS/MIB transmission of a legacy system.

It is also possible to design a PSS/SSS/MIB transmission of the NB-IoTsystem in a manner that avoids a PSS/SSS/MIB transmission of the LTEsystem as much as possible. For example, as illustrated in FIG. 9, S&Bsubframes 900 carrying an NB-IoT PSS/SSS/MIB and SIB subframes 902 maybe distributed appropriately. Alternatively, the NB-IoT PSS/SSS/MIBtransmission subframes 900 may be so designed as to avoid collision withLTE PSS/SSS/MIB symbols as much as possible. For example, unlike the LTEsystem, a PSS/SSS may be arranged in the last symbol of each subframe600.

FIG. 10 is an exemplary view illustrating an NB-IoT PSS/SSS/MIBtransmission in an LTE TDD system.

As illustrated in FIG. 10, an NB-IoT PSS/SSS/MIB 1000 may be so designedas to be transmitted only in a DL subframe 1010 or a special subframe1012 in the LTE TDD system. After accessing the LTE system and acquiringa TDD UL/DL configuration, an NB-IoT device may acquire usages of otherframes. Further, a control channel (for example, a PDCCH) and a datachannel (for example, a physical downlink shared channel (PDSCH)) ofNB-IoT may be configured to occupy only the DL subframe 1010 in LIE TDD.

FIG. 11 is an exemplary view illustrating an alternative DL framestructure in the time domain in the NB-IoT system.

For more feasible implementation of the in-band mode, the DL framestructure of the NB-IoT system may be matched to the DL frame structureof the L 1E system. Considering the in-band mode, the DL frame structureof the NB-IoT system mainly seeks not to affect legacy LTE UEs.Therefore, some REs need to be protected so that an NB-IoT device maynot use the REs.

Accordingly, it is useful to allocate a PSS/SSS and a PBCH to resourcesthat do not collide with a legacy LTE signal. A PSS, an SSS, and anM-PBCH of the NB-IoT system are arranged in a manner that avoidscollision with a CRS, a positioning reference signal (PRS), a PSS, anSSS, a PDCCH, a physical control format indicator channel (PCFICH), aphysical hybrid-ARQ indicator channel (PHICH), and a multicast broadcastsingle frequency network (MBSFN) of the LTE system. For example, the LTEMBSFN may occur in subframes 1, 2, 3, 6, 7 and 8. Herein, subframes 0,4, 5 and 9 may be considered as the positions of the NB-IoT PSS/SSS andPBCH.

As illustrated in FIG. 11, the frame structure of the NB-IoT system isidentical to that of the LTE system. The PSS of the NB-IoT system may bepositioned in subframe 9 1100 and repeated every 10 ms in order toprevent potential collision with the LIE MBSFN. The SSS may bepositioned in subframe 4 1102 and repeated every 20 ms. The PBCH may bepositioned in subframe 0 1104 and repeated every 10 ms. If there arededicated resources for transmission of SIB1, SIB1 may be positioned insubframe 4 1104 that is not occupied by the SSS. Considering theafore-described rules to avoid collision with a legacy LTE signal orchannel, it is obvious that other positions are also available. Theremaining resources except for resources used for transmission of thePSS, SSS, and SIB1 may be shared by a control channel (for example, aPDCCH) or a data channel (for example, a PDSCH).

C. Deployment of In-Band Mode or Guard-band Mode NB-IoT System

In an in-band mode NB-IoT system scenario, any PRB may be used basicallyfor an operation of the NB-IoT system. It may be assumed that an NB-IoTdevice has only information about the center frequency of the L 1Esystem, without bandwidth information. For the NB-IoT system operation,the following options for PRB configuration may be considered.

FIG. 12 is an exemplary view illustrating PRB access methods in anin-band mode NB-IoT system.

Exemplary in-band mode NB-IoT PRB access methods are illustrated in FIG.12. Herein, the positions of NB-IoT PRBs to be accessed are applicableonly to DL PRBs. UL PRB information may be signaled by DL broadcastinformation or control information.

Option 1:

Referring to FIG. 12(a), all PRBs (including center 6 RBs) may becandidate PRBs for operation of the NB-IoT system. An NB-IoT device mayblind-detect an NB-IoT signal in all possible PRBs (for example, PRBswithin an LTE bandwidth including up to 110 RBs in the in-band mode).

Option 2:

Referring to FIG. 12(b), all PRBs except for center 6 PRBs 1200 may becandidate PRBs for operation of the NB-IoT system. Since a legacy LTEsynchronization signal and broadcast channel are transmitted in thecenter 6 PRBs 1200, it may be preferable to exclude the center 6 PRBsfrom NB-IoT candidate PRBs. Otherwise, the NB-IoT system should bedesigned in consideration of avoidance of collision with a legacy L Esignal.

Since Option 1 and Option 2 impose almost no constraint on candidatePRBs for operation of the NB-IoT system, they require a very large blindsearch process for detection of an NB-IoT signal. Therefore, it may bebetter to pre-configure limited PRB sets for possible operations of theNB-IoT system.

Option 3:

Referring to FIG. 12(c), a pre-configured candidate PRB set for theNB-IoT system may be defined based on a PRB index offset related to acenter PRB. The index offset is equivalent to the frequency offset of anLTE center frequency, for example, {a₀, a₁, . . . , a_(N)}. Even thoughthere is no limit regarding exclusion of a specific PRB from a candidatePRB set, the candidate PRB set may be defined in consideration of an LTEsystem bandwidth and system requirements. Because different (or various)bandwidths are available to the LTE system, candidate PRBs need to bedefined for the different bandwidths.

Unlike Option 1 and Option 2, there may be a rule of selecting anappropriate candidate PRB in the case of different LTE bandwidths inOption 3. For example, edge PRBs (PRBs located at edges) 1210 and 1212in a given LTE system bandwidth may be considered for the NB-IoT systemusage. Selectively, the center 6 PRBs may be excluded in Option 3, as inOption 2. The NB-IoT device may blind-detect an NB-IoT signal in theseselected PRBs.

In the above options, a PRB may be an in-band PRB in a wide systembandwidth, but a guard-band PRB in a narrow system bandwidth. The NB-IoTdevice may behave differently in detecting an NB-IoT signal depending onan in-band PRB or a guard-band PRB. Therefore, additional modedifferentiation, that is, in-band mode or guard-band mode identificationis needed.

Option 4:

In view of the presence of a plurality of bandwidth options for the LTEsystem, an NB-IoT device may take a long time to perform the NB-IoT PRBblind detection procedure. Therefore, blind detection may be performedfor a shorter time by designing a 2-step access procedure.

Referring to FIG. 12(d), the NB-IoT device accesses a predefined verylimited set of PRBs 1220 (for example, one or two PRBs) in a first step.The PRB 1220 of step 1 may carry an NB-IoT synchronization signal and/orbroadcast information, and may be called an anchor PRB. The PRB 1220 mayprovide additional information about an in-band or guard-band NB-IoTsystem in the current LTE system/cell. Alternatively, a PRB in a guardband may be used as the anchor PRB. A PRB index for thein-band/guard-ban NB-IoT system in the LTE system (or LTE cell) may betransmitted by a synchronization signal or broadcast information in theanchor PRB. The additional information (for example, a cell ID, a systemframe number (SFN), a bandwidth (BW), and so on) may be included in theanchor PRB to help a device to access in the in-band or guard-band mode.

In a second step, the NB-IoT device may access an NB-IoT PRB 1222 usingthe PRB index of the NB-IoT system and the additional information, whichare acquired from the anchor PRB, and operate in the in-bandmode/guard-band mode.

FIG. 13 is an exemplary view illustrating use of a plurality of PRBs inthe in-band mode NB-IoT system.

A more specific example is illustrated in FIG. 13. A common anchor PRB1300 may be used to deliver a synchronization signal and broadcastinformation (an MIB and an SIB). A PRB index for a control channel and adata channel may be indicated by the common anchor PRB 1300. If thereare a plurality of PRBs for the data channel and the data channel, UEsmay be divided into different groups 1310 and 1320 in a predeterminedrule, and the UEs of the same group access the same control channelPRB/data channel PRB. For example, the UEs of group 1 1310 may access acontrol channel PRB 1312 and a data channel PRB 1314 of group 1 1310,and the UEs of group 2 1320 may access a control channel PRB 1322 and adata channel PRB 1324 of group 2 1320. In this manner, a traffic loadwithin a cell may be balanced.

FIG. 14 is an exemplary view illustrating a PRB blind detection methodin the NB-IoT system.

The position of a PRB related to a center frequency may be different fora different bandwidth. Accordingly, as illustrated in FIG. 14(a), acenter frequency 1400 may be positioned between two PRBs 1402 and 1404,or as illustrated in FIG. 14(b), a center frequency 1410 may bepositioned in the middle of one RB 1412. Therefore, two PRB blinddetection methods may be considered. The PRB blind detection methods area detection method having an offset of an integer multiple of a PRBbandwidth, and a detection method having an offset of an integermultiple of a PRB bandwidth and an additional offset of a ½ PRBbandwidth.

FIG. 15 is an exemplary view illustrating a PRB blind detection methodin a guard-band mode NB-IoT system.

As described before, some PRB may be an in-band PRB in a wide bandwidthbut a guard-band PRB in a narrow bandwidth. As illustrated in FIG. 15, aguard-band mode candidate PRB 1510 may be positioned near to an edge PRB1500 and have an offset of an integer multiple of 180 kHz.

D. NB-PSS/NB-SSS Design

FIG. 16 is an exemplary view illustrating a time synchronization methodbased on a PSS/SSS transmission in the NB-IoT system.

A narrow band PSS (NB-PSS) (PSS of NB-IoT) and a narrow band SSS(NB-SSS) (SSS of NB-IoT) may be transmitted so that a UE may acquiretime/frequency synchronization with a cell. Each of the NB-PSS andNB-SSS may be transmitted at a predefined density for a predeterminedperiod. For example, an NB-PSS 1600 is transmitted in one subframe everyM1 subframes (for example, M1=10 or 20), and an NB-SSS 1610 may betransmitted in one subframe every M2 subframes (for example, M2=10, 20or 40). The boundary of M1 subframes 1620 may be derived by NB-PSSdetection, and the boundary of M3 subframes 1640 may be derived byNB-SSS detection. Herein, M3 1640 may be an integer multiple of M2 1630.For example M1=20, M2=40, and M3=80. The boundary of the M3 subframesmay be aligned with the boundary of a narrow band PBCH (NB-PBCH: PBCH ofNB-IoT), to facilitate detection of the NB-PBCH.

Further, an NB-IoT device may need to acquire other system-specific orcell-specific information by receiving the NB-PSS 1600 and the NB-SSS1610. Other system-specific or cell-specific information may be, forexample, a CP length (when a system supports one or more CP lengths), aphysical cell ID (PCID), an FDD mode or TDD mode, and so on. The CPlength may be determined by blind detection. The PCID may be acquired byan NB-PSS index and an NB-SSS index. If N_(Total) ^(PSS) NB-PSS indexesand N_(Total) ^(SSS) NB-SSS indexes exist, N_(Total) ^(PSS) N_(Total)^(SSS) indications may exist. For example, if there are two NB-SSS sets,that is, NB-SSS1 and NB-SSS2, a combined indication may be expressed asN_(Total) ^(PSS/SSS)=N_(Total) ^(PSS)N_(Total) ^(SSS)=N_(Total)^(PSS)N_(Total) ^(SSS1)N_(Total) ^(SSS2).

E. Mode Differentiation or Mode Indication

To support access of the NB-IoT system to various modes, different modesmay be distinguished or indicated by the following options.

Option 1:

Synchronization sequences may be used to distinguish different NB-IoTmodes from each other. For example, since there are 3 PSS indexes and168 SSS indexes in the LTE system, a total of 504 (=3×168) cell IDs maybe supported. For the NB-IoT system, synchronization sequences may bedesigned in a similar manner. The numbers of PSS indexes and SSS indexesmay be designed based on requirements for the NB-IoT system. Althoughdifferent combinations of PSS indexes and SSS indexes (equivalent tocell IDs) may be used to indicate PCIDs, they may also be used todistinguish the NB-IoT operation modes from each other, along withPCIDs.

Option 1-1:

Since there are more SSS indexes than PSS indexes, different sets of SSSindexes may be used to distinguish different modes from each other. Thatis, a special case of extending SSS sets may be considered to supportmode indication. For example, SSSs having indexes {0, 1, 2, . . . , 167}may be used to indicate the in-band mode, which corresponds to the useof a set of LTE cell IDs {0, 1, 2, . . . , 503} for the in-bandoperation mode in the current LTE system. Other sets of SSS indexes maybe used to indicate the guard-band mode and the standalone mode. Forexample, a set of SSS indexes {168, 169, . . . , X} may be used toindicate the guard-band mode and the standalone mode. Herein, X is thelargest of SSS indexes for the NB-IoT system. It is to be noted that thesame basic SSS may be used for different SSS indexes, and a slightmodification may be made to distinguish different SSS indexes from eachother.

Option 1-2:

If there are one or more (for example, three) PSS indexes, different PSSindexes may be used to distinguish different modes from each other.Further, SSS indexes may be used to distinguish cells or sectors.

Option 1-3:

If it is assumed that there are 503 PCIDs in the LTE system and 3 NB-IoToperation modes are defined, 1512 indexes may be required to distinguishthe PCIDs and operation modes. If only two operation modes (that is, thein-band mode and a non-in-band mode) need to be distinguished from eachother, 1008 indexes may be required. The following index configurationmay be used for PCIDs and mode indication.

N _(ID) ^(PSS/SSS) =N _(Total) ^(Mode) N _(ID) ^(Cell,NB-IoT) +N _(ID)^(Mode)

Herein, N_(ID) ^(PSS/SSS)≤N_(Total) ^(PSS/SSS). That is, the number ofNB-PSS indexes and NB-SSS indexes used to indicate modes, N_(ID)^(PSS/SSS) is less than the total number of possible combinations ofNB-PSS indexes and NB-SSS indexes.

Examples of supporting indication of 2 or 3 modes will be described. Amethod for supporting indication of more modes may be extended in asimilar manner.

Example 1

If there are 504 PCIDs and 2-mode indication (in-band mode andnon-in-band mode, that is, N_(Total) ^(Mode)=2) is supported, N_(ID)^(PSS/SSS)=2N_(ID) ^(Cell,NB-IoT)+N_(ID) ^(Mode) where N_(ID)^(Cell,NB-IoT)∈[0,503] and N_(ID) ^(Mode)∈[0,1].

Example 2

If there are 504 PCIDs and 3-mode indication (in-band mode, guard bandmode, or standalone mode, that is, N_(Total) ^(Mode)=3) is supported,N_(ID) ^(PSS/SSS)=3N_(ID) ^(Cell,NB-IoT)+N_(ID) ^(Mode) where N_(ID)^(Cell,NB-IoT)∈[0,503] and N_(ID) ^(Mode)∈[0,2].

Option 2:

In the NB-IoT in-band operation mode, symbols of a control channel (forexample, LTE PDCCH symbols) and symbols occupied by RSs (for example,CRS symbols) may not be used for an NB-PSS/NB-SSS transmission. However,this limitation is not imposed on the NB-IoT guard-band mode andstandalone mode because the NB-IoT guard-band mode and standalone modeuse a band unused by the legacy system. Accordingly, an NB-IoT operationmode may be indicated by the density or position of a transmittedPSS/SSS. Herein, a PSS/SSS density may refer to the ratio of RE(s)occupied for transmission of a PSS/SSS in a unit resource area (forexample, one PRB).

FIG. 17 is an exemplary view illustrating a method for distinguishingdifferent operation modes from each other in terms of the positions anddensity of PSS/SSS symbols.

Option 2-1:

The PSS/SSS density in one subframe may be higher in the guard-band modeor standalone mode (see FIGS. 17(c) and 17(e)) than in the in-band mode(see FIG. 17(a)). That is, more symbols may be transmitted for a PSS/SSSin one subframe in the guard-band mode or standalone mode than in thein-band mode. Because symbol(s) used for a PDCCH in a subframe in theLTE system are not available for the in-band mode, an SSS may betransmitted in the first to third symbols of the subframe, for example,in the guard-band mode or standalone mode. Therefore, if an SSStransmission density is high in one subframe (for example, the SSStransmission density is equal to a PSS transmission density), it mayindicate the guard-band mode or standalone mode.

Option 2-2:

A mode may be indicated by a different PSS/SSS position in one subframe.For example, while an SSS is positioned only in a non-CRS symbol in thein-band mode, the SSS may also be positioned in a CRS symbol (forexample, 1700 or 1710). Therefore, an SSS positioned in a CRS symbol mayindicate the guard-band mode or standalone mode.

FIGS. 18 and 19 are exemplary views illustrating a method fordistinguishing different operation modes in terms of the positions anddensity of PSS/SSS subframes.

Option 2-3:

If a PSS occupies one subframe, an SSS may also occupy one subframe.Thus, it is possible to identify an operation mode based on thedensities or positions of a PSS subframe and an SSS subframe. Thedensity of PSS/SSS subframes may refer to the ratio of subframe(s)occupied for transmission of PSS/SSS subframes in a unit period (forexample, one frame or one superframe).

Referring to FIGS. 16 and 18, different NB-PSS subframe densities anddifferent NB-SSS subframe densities may be configured to distinguishoperation modes. For example, the transmission power of an NB-IoT devicemay be shared with a legacy LTE eNB in the in-band mode, and thuslimited transmission power may be configured for the in-band mode. Dueto this limited transmission power, the NB-PSS subframe density and theNB-SSS subframe density may be configured to be high in the in-bandoperation mode. Compared to the NB-PSS density in FIG. 18, the NB-PSSdensity is high in FIG. 16. Accordingly, the NB-PSS transmission of FIG.16 may indicate the in-band mode, whereas the NB-PSS transmission ofFIG. 18 may indicate the guard-band mode or standalone mode.

Referring to FIGS. 16 and 19, different positions of NB-PSS subframesand NB-SSS subframes may be configured to distinguish operation modes.There may be a limitation on the transmission positions of an NB-PSS andan NB-SSS in the in-band mode. For example, non-transmission of anNB-SSS in an LTE CRS symbol in FIG. 16 may indicate the in-band mode,whereas transmission of an NB-SSS in an LTE CRS symbol 1900 in FIG. 19may indicate the guard-band mode or standalone mode.

Option 3:

An NB-IoT operation mode may be explicitly indicated by broadcastinformation.

Option 3-1:

A ‘mode indication’ or ‘operation mode indication’ field in an NB-MIB(MIB of NB-IoT) may be used to indicate an NB-IoT operation mode. Forexample, if an operation mode indication by an NB-PSS or NB-SSS is notsupported, the ‘mode indication’ field may be added to an NB-MIBtransmitted on an NB-PBCH. If the ‘mode indication’ field is 1 bit, itmay indicate whether a mode is the in-band mode or not. If the ‘modeindication’ field is 2 bits, it may indicate the in-band mode, theguard-band mode, the standalone mode, and reserved.

FIG. 20 is an exemplary view illustrating a method for explicitlyindicating an NB-IoT mode by MIB payload (K=2).

If an NB-MIB is used to indicate an NB-IoT operation mode, the contentor interpretation of the NB-MIB may be different according to the NB-IoToperation mode. For example, predefined K (K>=1) most significant bits(MSBs) 2000 (or least significant bits (LSBs)) may be used to indicatean operation mode, and the content or interpretation of the remainingbits 2002 may be determined according to the operation mode.

FIG. 21 is an exemplary view illustrating another method for explicitlyindicating an NB-IoT mode by MIB payload (K=2).

As illustrated in FIG. 21, a mode indication field 2100 may bepositioned in an LSB (or MSB). Further, it is possible to separatecommon content 2102 from operation mode-related information 2104.

FIG. 22 illustrates a more specific example of MIB payload for differentoperation modes.

Referring to FIG. 22, a ‘mode indication’ field included in MIB payloadmay indicate one of an in-band (same cell ID or common cell ID) mode, anin-band (different cell ID) mode, the guard-band mode, and thestandalone mode. Specifically, the first bit 2200 of the mode indicationmay be used to indicate whether the operation mode is the in-band modeor not. If the first bit 2200 indicates that the operation mode is notthe in-band mode (that is, ‘0’), the next bit 2202 (that is, the secondbit) may be used to indicate the standalone mode or guard-band mode. Ifthe first bit 2200 indicates the in-band mode (that is, ‘1’), the secondbit 2200 may be used to different cases (for example, the cell ID of theNB-IoT system is identical to or different from that of the LTE system).That is, if different cases exist for any operation mode, the differentcases may be indicated along with the mode indication. For example, twocases may be supported for the in-band mode according to systemrequirements and planning. One of the cases is that the NB-IoT systemshares the same PCID with the LTE system, and the other case is that theNB-IoT system and the LTE system use different PCIDs. Therefore, thesetwo cases may be distinguished by the mode indication field 2200 and2202 included in the NB-MIB. If the cell ID (that is, PCID) is sharedbetween the NB-IoT system and the LTE system, CRS-related informationmay be indicated in the payload of the NB-MIB so that an NB-IoT devicemay use (or re-use) an LTE CRS for channel estimation.

Option 3-2:

Another field of an MIB or SIB, for example, a ‘Number of L 1E PDCCHSymbols’ field may be used to indicate a mode. If the value of theNumber of LTE PDCCH Symbols field is larger than 0, this may imply thatthe in-band mode is used, and if the value of the Number of LTE PDCCHSymbols field is 0, this may imply that the guard-band mode orstandalone mode is used.

Option 3-3:

Another field of the MIB or SIB, for example, a ‘Number of CRS AntennaPorts’ field for the legacy LTE system may be used to indicate a mode. A2-bit Number of CRS Antenna Ports field may indicate 0, 1, 2, and 4 asthe numbers of ports. If the number of antenna ports is indicated as 1,2, or 4, the in-band mode may be indicated, and if the number of antennaports is indicated as 0, the guard-band mode or standalone mode may beindicated. This approach may be applied to any other field. That is, a1-bit pattern may be reserved for mode indication.

Option 3-4:

A 1 or more-bit pattern may be reserved to indicate an NB-IoT operationmode in another field of the MIB. For example, if a PRB index isindicated in the MIB by means of a 5-bit pattern, a part of bit patternsmay be used to indicate actual PRB indexes, whereas the other bitpatterns may be used to indicate standalone or guard-band deployment.

When needed, a 1-bit ‘FDD/TDD mode indication’ field may be added to theNB-MIB transmitted on the NB-PBCH. Further, an additional bit may beused to indicate FDD mode or TDD mode configurations. For example, a3-bit ‘FDD/TDD mode indication’ field may indicate FDD, TDDconfiguration 0, TDD configuration 1, TDD configuration 2, TDDconfiguration 3, TDD configuration 4, TDD configuration 5, and TDDconfiguration 6.

Further, combinations of the above options may be used to indicate aplurality of modes such as an FDD/TDD mode and an NB-IoT operation mode.

FIG. 23 is a flowchart illustrating a method for identifying a mode inan NB-IoT device.

The NB-IoT device may detect an NB-PSS and an NB-SSS, or an NB-MIB(2300).

The device may determine an NB-IoT operation mode using the detectedNB-PSS and NB-SSS, or the detected NB-MIB (2302). For example, a 1-bitmode indication may be embedded in the NB-MIB, and the device maydetermine from the 1-bit mode indication whether the current operationmode is the in-band mode or not. Then, the NB-IoT device may performdifferent processing according to the determined operation mode.

If the determined operation mode is the in-band operation mode, thedevice may operate in the in-band mode (2304). In the in-band operationmode, a predefined number of (for example, 3) LIE PDCCH symbols in onesubframe may not be used by the NB-IoT system. If the determinedoperation mode is not the in-band operation mode, the device may operatein the guard-band mode or standalone mode (2306). In the guard-band modeor standalone mode, the constraint for the in-band mode is not imposedon processing.

Considering the features of different operation modes, the above optionsfor mode indication are useful for appropriate subsequent processingbecause the options enable the NB-IoT system to distinguish NB-IoToperation modes from each other as fast as possible.

FIG. 24 is a flowchart illustrating another method for identifying amode in an NB-IoT device.

The NB-IoT device may detect an NB-PSS and an NB-SSS, or an NB-MIB(2400).

The device may determine an NB-IoT operation mode using the detectedNB-PSS and NB-SSS, or the detected NB-MIB (2402 and 2406). For example,a 2-bit mode indication may be embedded in the NB-MIB, and the devicemay determine from the 2-bit mode indication whether the currentoperation mode is the in-band mode, the guard-band mode, or thestandalone mode.

First, the device may determine whether the NB-IoT mode is the in-bandmode (2402). If the determined NB-IoT mode is the in-band mode, thedevice may operate in the in-band mode (2404). In the in-band operationmode, a predefined number of (for example, 3) LTE PDCCH symbols in onesubframe may not be used by the NB-IoT system. If the determinedoperation mode is not the in-band operation mode, the device maydetermine whether the NB-IoT operation mode is the guard-band mode(2406). If the determined operation mode is the guard-band operationmode, the device may operate in the guard-band mode (2408). If thedetermined operation mode is not the guard-band operation mode, thedevice may operate in the standalone mode (2410).

FIG. 25 is a flowchart illustrating another method for identifying amode in an NB-IoT device.

In FIG. 25, an MIB may just indicate whether an operation mode is thein-band mode or not. If the guard-band mode and the standalone mode needto be further distinguished, it may be determined whether the operationmode is the guard-band mode or the standalone mode by reception of anSIB (for example, SIB1).

The NB-IoT device may detect an NB-PSS and an NB-SSS, or an NB-MIB(2500).

The device may determine an NB-IoT operation mode using the detectedNB-PSS and NB-SSS, or the detected NB-MIB (2502). For example, a 1-bitmode indication may be embedded in the NB-MIB, and the device maydetermine from the 1-bit mode indication whether the current operationmode is the in-band mode or not.

If the determined operation mode is the in-band operation mode, thedevice may operate in the in-band mode (2504). If the determinedoperation mode is not the in-band operation mode, the device may receivean SIB (2506).

The device may determine from the received SIB whether the NB-IoToperation mode is the guard-band mode (2508). If the determinedoperation mode is not the guard-band mode, the device may operate in thestandalone mode (2512).

FIG. 26 is a flowchart illustrating another method for identifying amode in an NB-IoT device.

The mode differentiation method of FIG. 26 may be applied to the casewhere the NB-MIB mode indication field illustrated in FIG. 22 is used.An NB-IoT device may detect an NB-MIB, and then acquire operation modeinformation and related parameters (for example, channel information,CRS-related information, and so on) for further processing.

The NB-IoT device may detect an NB-PSS and an NB-SSS, or an NB-MIB(2600).

The device may determine an NB-IoT operation mode using the detectedNB-PSS and NB-SSS, or the detected NB-MIB (2602). For example, the 1-bitmode indication 2200 may be embedded in the NB-MIB, and the device maydetermine from the 1-bit mode indication 2200 whether the currentoperation mode is the standalone mode (2602).

If the determined NB-IoT mode is the standalone mode, the device mayoperate in the standalone mode (2604). If the determined operation modeis not the standalone mode, the device may determine from the additional1-bit mode indication 2202 whether the NB-IoT operation mode is theguard-band mode (2606). If the determined operation mode is theguard-band operation mode, the device may operate in the guard-band mode(2608). If the determined operation mode is not the guard-band operationmode, the device may determine whether the NB-IoT operation mode is thein-band mode and uses the same cell ID as that of the legacy system fromthe 1-bit mode indication 2200 and the additional 1-bit mode indication2202 (2610). If the determined operation mode is the in-band mode withthe same cell ID, the device may operate in the in-band mode (the samePCID) (2612). If the determined operation mode is the in-band mode but adifferent cell ID is used, the device may operate in the in-band mode (adifferent PCID) (2612).

F. Alternative Design of NB-IoT Frame Structure

FIG. 27 is an exemplary view illustrating an alternative design of anNB-IoT downlink frame structure.

The alternative NB-IoT DL frame structure will be described. Thisstructure is matched to an LTE system, for suitable in-band deployment.Considering the in-band mode, the NB-IoT frame structure mainly seeksnot to affect legacy LIE UEs. Therefore, some REs need to be protectedso that they may not be used for NB-LTE.

Therefore, it is preferable to allocate a PSS/SSS and a PBCH in a mannerthat avoids collision with a legacy LTE signal in resources. A PSS, anSSS, and an M-PBCH may be selected so as to avoid collision with an LTECRS, PRS, PSS, SSS, PDCCH, PCFICH, PHICH, and MBSFN. For example, theLTE MBSFN may occur in subframes 1, 2, 3, 6, and 7. Herein, subframes 0,4, 5 and 9 may be considered as the positions of the NB-IoT PSS/SSS andPBCH.

As illustrated in FIG. 27, the NB-IoT frame structure may be designed inthe same manner as the LIE frame structure. A PSS 2700 may be positionedin subframe 9 and repeated every 10 ms in order to prevent potentialcollision with the MBSFN. An SSS 2702 may be positioned in subframe 4and repeated every 20 ms. A PBCH 27204 may be positioned in subframe 9and repeated every 10 ms. If there are dedicated resources fortransmission of SIB1, SIB1 2706 may be positioned in subframe 4 that isnot occupied by the SSS. Considering the afore-described rules to avoidcollision with legacy L 1E, it is obvious that other positions are alsoavailable. The remaining resources except for resources used fortransmission of the PBCH, PSS, SSS, and SIB1 may be shared by a controlchannel (for example, a PDCCH) or a data channel (for example, a PDSCH).

FIG. 28 is an exemplary view illustrating a method for supporting NB-IoTcommunication in a base station according to the present disclosure.

In a cellular system, a base station may transmit a synchronizationsequence to an NB-IoT device so that the NB-IoT device may acquiresynchronization with the base station (2800). The synchronizationsequence may include a PSS and/or an SSS.

The base station may transmit system information including a ‘modeindication’ field indicating one operation mode to the NB-IoT device(2805). The mode indication field may include 2 bits. A first bit mayindicate whether the operation mode is the in-band mode or not, and asecond bit may indicate whether the operation mode is the guard-bandmode or the device uses the same PCID as that of the legacy system.Operation modes that may be indicated by the mode indication field mayinclude the standalone mode, the guard-band mode, the in-band mode-samePCID, and the in-band mode-different PCID. The system information may bean MIB transmitted on a PBCH. The MIB may include information about atransmission PRB index of the control channel or data channel. Payloadof the MIB may further include information related to the in-band mode,for example, CRS-related information of the LTE system. Selectively, theMIB may be transmitted in an anchor PRB at a predefined position.Herein, the standalone mode is a mode in which the NB-IoT deviceoperates within the bandwidth of another cellular system (for example, aGSM system), the guard-band mode is a mode in which the NB-IoT deviceoperates within a guard band of the cellular system, and the in-bandmode is a mode in which the NB-IoT device operates within the bandwidthof the cellular system.

The base station may transmit the control channel and/or the datachannel based on parameters related to NB-IoT included in the systeminformation (2810).

FIG. 29 is an exemplary view illustrating a method for conducting NB-IoTcommunication in a device according to the present disclosure.

An NB-IoT device may receive a synchronization sequence from a basestation of a cellular system so that the NB-IoT device may acquiresynchronization with the base station (2900). The synchronizationsequence may include a PSS and/or an SSS.

The device may receive, from the base station, system informationincluding a ‘mode indication’ field indicating one operation mode to theNB-IoT device (2905). The mode indication field may include 2 bits. Afirst bit may indicate whether the operation mode is the in-band mode ornot, and a second bit may indicate whether the operation mode is theguard-band mode or the device uses the same PCID as that of the legacysystem. Operation modes that may be indicated by the mode indicationfield may include the standalone mode, the guard-band mode, the in-bandmode-same PCID, and the in-band mode-different PCID. The systeminformation may be an MIB transmitted on a PBCH. The MIB may includeinformation about a transmission PRB index of the control channel ordata channel. Payload of the MIB may further include information relatedto the in-band mode, for example, CRS-related information of the LTEsystem. Selectively, the MIB may be transmitted in an anchor PRB at apredefined position. Herein, the standalone mode is a mode in which theNB-IoT device operates within the bandwidth of another cellular system(for example, a GSM system), the guard-band mode is a mode in which theNB-IoT device operates within a guard band of the cellular system, andthe in-band mode is a mode in which the NB-IoT device operates withinthe bandwidth of the cellular system.

The device may receive the control channel and/or the data channel basedon parameters related to NB-IoT included in the system information(2910).

FIG. 30 is a block diagram of a base station according to the presentdisclosure.

A base station 3000 may include a transceiver 3005 for transmitting andreceiving signals to and from a device, and a controller 3010 forcontrolling overall operations of the base station 3000. All operationsof the base station described above in the present disclosure may beunderstood as performed under the control of the controller 3010.However, the controller 3010 and the transceiver 3005 are notnecessarily configured as separate devices. Rather, the controller 3010and the transceiver 3005 may be integrated into one component in theform of a single chip.

FIG. 31 is a block diagram of a device according to the presentdisclosure.

A device 3100 may include a transceiver 3105 for transmitting andreceiving signals to and from a base station, and a controller 3110 forcontrolling overall operations of the device 3100. All operations of thedevice described above in the present disclosure may be understood asperformed under the control of the controller 3110. However, thecontroller 3110 and the transceiver 3105 are not necessarily configuredas separate devices. Rather, the controller 3110 and the transceiver3105 may be integrated into one component in the form of a single chip.

It is to be noted that the configurations of transmission resources, thedeployment methods, the mode indication methods, the deviceconfigurations, and so on illustrated in FIGS. 1 to 31 by way of exampleare not intended to limit the scope of the present disclosure. That is,all components or steps illustrated in FIGS. 1 to 31 should not beinterpreted as mandatory components for implementation of the presentdisclosure, and the present disclosure may be implemented even with apart of the components without departing from the scope and spirit ofthe present disclosure.

The afore-described operations may be performed by providing a memorydevice storing a corresponding program code in a component of a basestation, a device, or a terminal device in a communication system. Thatis, a controller of the base station, device, or terminal device mayperform the afore-described operations by reading the program codestored in the memory by a processor or a central processing unit (CPU)and executing the program code.

Various components and modules of a base station, device, or terminaldevice described in the present disclosure may operate using hardwarecircuits such as a combination of a hardware circuit such as acomplementary metal oxide semiconductor-based logic circuit, firmware,and software and/or hardware and firmware and/or software embedded in amachine-readable medium. For example, various electrical structures andmethods may be implemented using electrical circuits such astransistors, logic gates, and ASICs.

While the disclosure has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the disclosure asdefined by the appended claims and their equivalents.

1. A method in a base station for supporting narrow band Internet ofthings (IoT) communication of a device in a cellular system, the methodcomprising: transmitting system information including a 2-bits modeindication field indicating an operation mode for the narrow band IoTcommunication, the operation mode corresponding to one of a plurality ofoperations modes; and transmitting a control channel and a data channelbased on the system information, wherein the operation modes include atleast one of a guard-band mode or an in-band mode.
 2. (canceled)
 3. Themethod of claim 1, wherein the system information is a masterinformation block (MIB) broadcast on a physical broadcast channel(PBCH).
 4. The method of claim 1, wherein a first bit of the 2-bits modeindication field indicates whether the in-band mode is configured. 5.The method of claim 4, wherein a second bit of the 2-bits modeindication field indicates whether the guard-band mode is configured orwhether a common cell identifier (ID) is used for the cellular systemand the narrow band IoT communication.
 6. The method of claim 1, whereinthe system information further includes additional information relatedto the operation mode of the narrow band IoT communication.
 7. Themethod of claim 1, wherein the system information further includes anindex of a physical resource block (PRB) carrying the control channeland the data channel.
 8. The method of claim 1, wherein the systeminformation is transmitted in an anchor PRB at a predetermined position.9. The method of claim 1, wherein the narrow band IoT communication isone of enhanced mobile broadband (eMBB) communication of a 5^(th)generation (5G) system, narrow band IoT (NB-IoT) communication of a longterm evolution (LTE) system, or massive machine type communication(mMTC).
 10. A base station for supporting narrow band Internet of things(IoT) communication of a device in a cellular system, the base stationcomprising: a controller configured to control transmission of systeminformation including a 2-bits mode indication field indicating anoperation mode for the narrow band IoT communication, the operation modecorresponding to one of a plurality of operations modes, andtransmission of a control channel and a data channel based on the systeminformation; and a transceiver configured to transmit the systeminformation, the control channel, and the data channel, under thecontrol of the controller, wherein the operation modes include at leastone of a guard-band mode or an in-band mode.
 11. The base station ofclaim 10, wherein the system information is a master information block(MIB) broadcast on a physical broadcast channel (PBCH).
 12. The basestation of claim 11, wherein a first bit of the 2-bits mode indicationfield indicates whether the in-band mode is configured.
 13. A device forperforming narrow band Internet of things (IoT) communication in acellular system, the device comprising: a controller configured tocontrol reception of system information including a 2-bits modeindication field indicating an operation mode for the narrow band IoTcommunication, the operation mode corresponding to one of a plurality ofoperations modes, and reception of a control channel and a data channelbased on the system information; and a transceiver configured to receivethe system information, the control channel, and the data channel underthe control of the controller, wherein the operation modes include atleast one of a guard-band mode or an in-band mode.
 14. The device ofclaim 13, wherein the system information is a master information block(MIB) broadcast on a physical broadcast channel (PBCH).
 15. The deviceof claim 14, wherein a first bit of the 2-bits mode indication fieldindicates whether the in-band mode is configured.
 16. A method in adevice for performing narrow band Internet of things (IoT) communicationin a cellular system, the method comprising: receiving systeminformation including a 2-bits mode indication field indicating anoperation mode for the narrow band IoT communication, the operation modecorresponding to one of a plurality of operations modes; and receiving acontrol channel and a data channel based on the system information,wherein the operation modes include at least one of a guard-band mode oran in-band mode.
 17. The method of claim 16, wherein the systeminformation is a master information block (MIB) broadcast on a physicalbroadcast channel (PBCH).
 18. The method of claim 16, wherein a firstbit of the 2-bits mode indication field indicates whether the in-bandmode is configured.
 19. The method of claim 18, wherein a second bit ofthe 2-bits mode indication field indicates whether the guard-band modeis configured or whether a common cell identifier (ID) is used for thecellular system and the narrow band IoT communication.
 20. The method ofclaim 16, wherein the system information further includes additionalinformation related to the operation mode of the narrow band IoTcommunication.
 21. The method of claim 16, wherein the systeminformation further includes an index of a physical resource block (PRB)carrying the control channel and the data channel.